/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You under the Apache License, Version 2.0
 *  (the "License"); you may not use this file except in compliance with
 *  the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.harmony.security.x509;

import java.io.IOException;
import java.util.Iterator;
import java.util.List;

import org.apache.harmony.security.asn1.ASN1Oid;
import org.apache.harmony.security.asn1.ASN1SequenceOf;
import org.apache.harmony.security.asn1.ASN1Type;
import org.apache.harmony.security.asn1.BerInputStream;
import org.apache.harmony.security.asn1.ObjectIdentifier;

/**
 * Extended Key Usage Extension (OID == 2.5.29.37).
 * 
 * The ASN.1 definition for Extended Key Usage Extension is:
 * 
 * <pre>
 *  id-ce-extKeyUsage OBJECT IDENTIFIER ::= { id-ce 37 }
 * 
 *  ExtKeyUsageSyntax ::= SEQUENCE SIZE (1..MAX) OF KeyPurposeId
 * 
 *  KeyPurposeId ::= OBJECT IDENTIFIER
 * </pre>
 * 
 * (as specified in RFC 3280 http://www.ietf.org/rfc/rfc3280.txt
 */
public class ExtendedKeyUsage extends ExtensionValue {

	// the value of extension
	private List keys;

	/**
	 * ASN.1 Encoder/Decoder.
	 */
	public static final ASN1Type ASN1 = new ASN1SequenceOf(new ASN1Oid() {

		@Override
		public Object getDecodedObject(BerInputStream in) throws IOException {
			final int[] oid = (int[]) super.getDecodedObject(in);
			return ObjectIdentifier.toString(oid);
		}

	});

	/**
	 * Creates the extension object on the base of its encoded form.
	 */
	public ExtendedKeyUsage(byte[] encoding) {
		super(encoding);
	}

	/**
	 * Creates an object on the base of list of integer arrays representing key
	 * purpose IDs.
	 */
	public ExtendedKeyUsage(List keys) {
		this.keys = keys;
	}

	/**
	 * Places the string representation of extension value into the StringBuffer
	 * object.
	 */
	@Override
	public void dumpValue(StringBuffer buffer, String prefix) {
		buffer.append(prefix).append("Extended Key Usage: "); //$NON-NLS-1$
		if (keys == null) {
			try {
				keys = getExtendedKeyUsage();
			} catch (final IOException e) {
				// incorrect extension value encoding
				super.dumpValue(buffer);
				return;
			}
		}
		buffer.append('[');
		for (final Iterator it = keys.iterator(); it.hasNext();) {
			buffer.append(" \"").append(it.next()).append('"'); //$NON-NLS-1$
			if (it.hasNext()) {
				buffer.append(',');
			}
		}
		buffer.append(" ]\n"); //$NON-NLS-1$
	}

	/**
	 * Returns the encoded form of the object.
	 */
	@Override
	public byte[] getEncoded() {
		if (encoding == null) {
			encoding = ASN1.encode(keys);
		}
		return encoding;
	}

	/**
	 * Returns the list of string representation of OIDs corresponding to key
	 * purpose IDs.
	 */
	public List getExtendedKeyUsage() throws IOException {
		if (keys == null) {
			keys = (List) ASN1.decode(getEncoded());
		}
		return keys;
	}
}
